How can i Mirror more than one objects at the same time?
Download Smart Join Addon

Select the mesh (wheel) and click on smart join (it temporary join all the selected mesh). You can now move all the join mesh and add any modifier to all the join mesh. 
If you want to separate the mesh just click the separate s. join

If you want to edit the join mesh click on the expand smart join and after finishing the editing click on collapse smart join.